Physics in other branches of science

biology of a tree explained by physics

Students of many fields find themselves studying physics in one way or another because of the basic role it plays in all of the physical phenomena. For example, one can possibly see biology from a viewpoint of physics but in terms of living things. Similarly, chemistry is the physics of chemical compounds.

Let us consider the life cycle of a tree as an example.

It is known to us that seed sown in the ground develops the shoot of a plant which grows towards the sun. At the same time, root of the plant also starts to spread deeper in the soil. The factors which influence this process of germination include temperature, water, oxygen and light.

Since the soil has a higher concentration of water than the root cells, the water from the soil travels through the membrane into the roots. From the roots, water enters into the woody stem of the tree and then into the leaves.

While some of the water is used up during photosynthesis, most of it is turned into vapour, the gaseous phase of water, which escapes from the leaves. Because water molecules within the stem tend to stick together due to cohesion, the vapour that escapes from the leaves drags the water in the roots and stems upwards behind it.

This mechanism by which plants sort of drink water is called transpiration and it continues as long as there is life in the tree.

biology of a tree explained by physics
Journey of water molecules from ground to air

Now, where does the structure of the tree come from? Surely from the ground, you will say. But not really. Apart from water and other handful of nutrients, soil contributes no more in the building up of the tree. The mass of the tree is in fact primarily carbon which is stored in organic form.

Let us understand how so.

Just like we breathe in oxygen, a tree is known to soak up carbon dioxide from the atmosphere so as to live. This acted upon by the sunlight enables the tree to extract carbon from carbon dioxide and store large quantities of it in their tissues such as in fruits.

This is possible because of a procedure called photosynthesis by which plants convert light energy into chemical energy and store this chemical energy within themselves in the form of glucose therefore growing in size and structure each year.

All plants absorb carbon dioxide but trees absorb the most, which is why, they are bigger and also why it is advised to plant more and more of them so as to offset global warming. Thus, a combination of water, air and sunlight mediate the growth and the flowering of the tree.

biology of a tree explained by physics
A fully grown and flowering tree

At the end of its life, a tree is cut and its wood used as fuel for combustion. During combustion, the carbon is combining with the surrounding oxygen in a terrible catastrophe, fire, producing light and heat as a result. This light and heat is in fact the light and heat of the sun which was originally stored in the tree.

Thus, nature comes back in a full circle.

The cohesion or linkage between water molecules, creation of a kind of a pressure in the stem due to evaporation in the leaves, and as a result, pulling up water from the ground. Conversion of energy from one form to another in a chemical reaction and then restoration of the same energy in another chemical process of burning.

From our example of tree, we have seen that in biological as well as in chemical processes physics has a role to play.


  1. Very well composed information.

  2. I wonder from where all this system came into being.Who used principles of Physics,Chemistry,as we know now ,to build up this nature and living beings?A great Mystry.That's why I feel comfortable to believe in Supreme system,one can name it as GOD.